The agency also said it was unable to resolve all the issues it was considering because the engineer — whom it referred to in its report on the inquiry as Engineer Doe — cited his Fifth Amendment right and declined to talk.

Now a former state investigator involved in another inquiry into Street View has identified Engineer Doe. The former investigator said he was Marius Milner, a programmer with a background in telecommunications who is highly regarded in the field of Wi-Fi networking, essential to the project.

The former state investigator spoke on the condition that he not be identified because he was not authorized to speak. Although the F.C.C. declined to identify the engineer, a footnote in the full text of its report said Google told the agency the identity of Engineer Doe “only because it had disclosed his name to state investigators on December 17, 2010.”

Google declined to comment.

Mr. Milner, in a brief conversation on his doorstep in Palo Alto, Calif., Sunday night, said he could not answer any questions. He recommended calling a lawyer, Martha Boersch, who he said represented him. “She speaks for me,” he said.

Ms. Boersch declined to comment Monday. A solo practitioner, her work focuses on state and federal false claims act, fraud, antitrust and securities cases. She worked as a federal prosecutor in San Francisco from 1992 to 2004.

The Street View project was an ambitious plan to photograph and map the world’s streets that also involved gathering information about local wireless networks to improve location-based searches.

A Google engineer went a step further, however, the F.C.C. report said, and included code to collect unencrypted data sent from homes by computers — e-mails and Internet searches — as specially equipped cars drove by. That data collection occurred from 2007 to 2010.

Google long maintained that the engineer was solely responsible for this aspect of the project, which resulted in official investigations, some still unresolved, in more than a dozen countries. But a complete version of the F.C.C.’s report, released by Google on Saturday, has cast doubt on that explanation, saying that the engineer informed at least one superior and that seven engineers who worked on the code were all in a position to know what was going on.

The F.C.C. report also had Engineer Doe spelling out his intentions quite clearly in his initial proposal. Managers of the Street View project said they never read it.

Depicting his actions as the work of a rogue “requires putting a lot of dots together,” Mr. Milner said enigmatically Sunday before insisting again he had no comment. He said he was closely following the news reports on the issue.

Before joining Google in 2003, Mr. Milner worked at Lucent Technologies and Avaya, communications and computer networking companies, according to his LinkedIn page.

Mr. Milner created a program called “NetStumbler,” the page also says, and describes the early version of NetStumbler as “the world’s first usable ‘Wardriving’ application for Windows.”

The F.C.C. report notes that wardriving is “the practice of driving streets and using equipment to locate wireless local-area networks using Wi-Fi, such as wireless hot spots at coffee shops and home wireless networks.”

The engineer — Mr. Milner’s LinkedIn entry says he has worked at Google’s YouTube subsidiary since November 2008 — wrote the code during the 20 percent of work time that the company gives employees to pursue ideas on their own, Google told the F.C.C., according to the agency’s full report.

In 2010, after it became clear that Google’s Street View project was collecting e-mail and other personal data, Google hired a computer investigations firm, Stroz Friedberg, to examine how the software program worked.

The outside investigator’s report was named, “Source code analysis of gstumbler,” the name for the Street View application initially used inside Google. The Stroz Friedberg report does not name the developer of the gstumbler program, or other engineers who worked on Street View. Stroz Friedberg declined to comment on its work for Google.

Locating and communicating effectively with Wi-Fi networks is an essential capability for mobile computing. It is an important tool in smartphone software like Google’s Android, Apple’s iOS and Microsoft’s Windows Phone, both for communicating and often for location-based services like shopping guides and Foursquare, an application that shows users when friends are nearby.

Data beamed from wireless networks guide those location services. But, according to industry executives and analysts, there are different approaches to using Wi-Fi transmissions. The minimal approach, they say, is to collect data on the access point and strength of the signal. That is the equivalent of the Wi-Fi network saying, “Here I am, and here’s what I can do.”

Skyhook is suing Google, contending that it pressured smartphone makers to drop commitments to use the firm’s location software. Google denies the charges, and the suit is pending.

A few years ago, Mr. Morgan said, Skyhook looked at whether gathering more data would help pinpoint locations more accurately. After conducting some experiments, his specialist firm failed to see a benefit for location services.

Mr. Morgan participated on an F.C.C. panel last June on privacy and location data in general, but he was not deposed as part of the agency’s investigation.

Other analysts are skeptical about the “lone engineer” explanation that Google clung to for so long. But they say that for an internal project, like Street View, a small group of engineers, working independently, was probably responsible. That is especially true at Google, where engineers rule and data is viewed as a precious asset.

“This is the thinking of an engineer — grab the data and worry about filtering it out later,” said Al Hilwa, a former software developer and manager, who is an analyst at the research firm IDC. “That’s the engineering mind-set, especially at Google.”

A version of this article appears in print on May 1, 2012, on Page B1 of the New York edition with the headline: Data Engineer In Google Case Is Identified. Order Reprints|Today's Paper|Subscribe